Temperature-controlled spindle for centrifuges and similar apparatus

ABSTRACT

An oil and air cooled rotating spindle. By means of an oil flow path, heat sinks and air-cooled surfaces, the spindle during operation may be constantly maintained at or near ambient temperature thus preventing any changes in temperature of the apparatus rotated by the spindle and hence in any material contained in the apparatus.

United States Patent Inventor Appl. No.

Filed Patented Assignee TEMPERATURE-CONTROLLED SPINDLE FOR CENTRIFUGES AND SIMILAR APPARATUS 9 Claims, 3 Drawing Figs.

US. Cl 308/76, 308/ l87 Int. Cl Fl6c 37/00, Flc 33/66 Field of Search 308/76, 77, 134.1, 169

lllll 1 References Cited UNlTED STATES PATENTS Else 308/l34.1 X Waterflll 308/l34.l X

Stafford 308/76 Ponomareff..... 308/134. 1 Luenberger..... 308/77 Kuznetsov 308/15 2 Primary Examiner-Fred C. Mattern, Jr Assistant Examiner-Frank Susko Att0rney-Bessie A. Lepper PATENTEUSEPMIHII 3504.769

lNVh'NTOR.

Allen Lothom, Jr.

PAIENTED SEPI4|97| 3504.759

I saw a nr 2 INVENTOR.

Allen Lothom, Jr.

-Atmmey TEMPERATURE-CONTROLLED SPINDLE FOR CENTRIFUGES AND SIMILAR APPARATUS This invention relates to a centrifuge spindle assembly capable of operating continuously at relatively high speeds while remaining at essentially ambient temperature.

In the processing of certain liquids, e.g., blood, pharmaceutical liquids, cell suspensions and the like it may be necessary to centrifuge the liquids, As a particular example, whole blood is centrifuged to separate the cells from the plasma. In the case of blood processing, it is of primary importance that the temperature of the cells be held below normal body temperature. This in turn requires that all of the treating liquids used and all of the equipment employed be maintained at a relatively constant ambient temperature. This is generally accomplished by keeping all such liquids and equipment in a temperature-controlled room to permit them to reach the desired thermal equilibrium prior to their contacting the blood to be processed. It is also, of course, necessary to maintain the blood during processing at or near ambient temperature, a fact which makes it necessary to have centrifuges of a type which does not heat the blood during processing.

Apparatus such as centrifuges normally generate frictional heat at the spindle bearings and unless special measures are taken this heat will be transferred to the material being centrifuged. In the case of blood, the transfer of such heat to the blood may inflict irreparable damage to the blood constituents. Such damage is customarily prevented or minimized by enclosing the centrifuge in a mechanically refrigerated chamber with individual temperature control, an arrangement which requires integral refrigerating equipment as well as technical attention to be sure it is operating correctly.

It would therefore be desirable to have a centrifuge spindle along with its associated components which did not generate so much heat as to require auxiliary mechanical refrigeration and which remains near ambient temperature without use of individual thermostats, thus eliminating the presently used integral refrigeration and temperature control equipment. The apparatus of this invention provides means for maintaining that portion of the spindle adjacent to those rotational parts which contact the liquid being centrifuged at substantially ambient temperature. By circulating ambient air as a fluid to cool an extended heat transfer surface which in turn is in heat transfer relationship with bearing cooling oil, the centrifuge spindle is continuously maintained at substantially the same temperature as its environment.

It is therefore a primary object of this invention to provide a centrifuge spindle which may be rotated at speeds of about 5,000 rpm. without experiencing any appreciable rise in temperature above ambient. It is still another object of this invention to provide a spindle assembly particularly well adapted for use in a centrifuge used to process blood. It is another primary object of this invention to provide a method for continuously maintaining a centrifuge spindle at essentially the same temperature as the ambient air surrounding it. It is a further object to provide a method of the character described which permits blood to be centrifuged at a temperature which remains below body temperature. Other objects of the invention will in part be obvious and will in part be apparent hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combination of elements and arrangement of parts which are adapted to effect such steps, all as exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which FIG. 1 is a vertical cross section through the spindle assembly of this invention;

FIG. 2 is a cross section of the oil pump section of the spindle assembly of FIG. 1 taken along line 22 of that figure; and

FIG. 3 is a cross section of the heat transfer fin section of the spindle assembly of FIG. 1 taken along line 3-3 of that figure.

In the spindle assembly of this invention, ball bearings are lubricated with a relatively low-viscosity oil which is centrifugally pumped for rapid circulation over the ball bearing and then over the surface area within the bearing housing. The bearing housing is, in turn, thermally bonded to extended heat transfer surfaces which are maintained at substantially constant temperature by continuously contacting ambient air with them. An additional feature of the spindle assembly is the incorporation of elastic bearing mounting means to ease the local and frictional heat generated in the bearing due to minor unbalance of the rotating parts.

The spindle assembly may be described in detail with reference to the drawings. As seen in FIG. I the centrifuge spindle 10, preferably having a minimum diameter consistent with practical use, is maintained in alignment by upper bearing means 11 and lower bearing means 12. Associated with the upper bearing means is an oil pump 13, and with the central portion of the spindle a heat transfer system 14. Means for driving the spindle are generally indicated by the numeral 15. A portion of the centrifuge chuck which is driven by the spindle is indicated at 16. This chuck is preferably one which is described in my copending application, Ser. No. 761,558 filed Sept. 23, 1968.

The spindle 10 is encased in a spindle bearing spacer 20. At its upper end the spacer 20 gives way to a rotor 21 having a plurality of oil passage 22 drilled therethrough. The rotor 21 has an extended skirt 23 which is slightly inclined downwardly toward the spindle axis. An annular ring 24 having an upwardly extending annular sleeve 25 integral with its inner periphery forms an oil chamber 26 with a heavy-walled tubing 27 surrounding substantially the entire length of the spindle. The upper bearing means 11 terminates the oil chamber 26. A clearance 30 is maintained between the rotating bearing spacer 20 and the stationary annular sleeve 25.

The inclined skirt 23 serves as a pump rotor which picks up oil collected immediately above ring 24. This oil is pumped by centrifugal force through the oil passages 22 to contact the upper bearing means 11 before flowing downwardly over the inner surface 34 of the heavy-walled tubing through chamber 26 for reentry into oil pump rotor skirt 23. The rotating assembly of collar piece 21 and its skirt 23, the dam 24 and the passages defined within chamber 26 make up an oil pump which is of a well-known design.

Oil is introduced into the pump through a suitable oil line 35 which is also in fluid communication with an oil level gage 36 having a transparent viewing window 37. Air vents 38 and 39 serve to maintain ambient air pressure within the spindle housing so that the air pressure over the oil in gage 36 is equal to the air pressure in the spindle housing.

The upper bearing means 11, comprising the rotating inner spindle bearing 40, ball bearings 41, and the outer stationary bearing ring 42 is constructed in accordance with known bearing art. An annular ring 43 formed of an elastomeric material serves as a spindle bearing flexible mount to permit flexible accommodation to any unbalance of the rotating parts and to reduce the load on bearing means 11 which in turn reduces the amount of heat that must be dissipated.

The heat transfer system 14 is comprised of fins 48 which are attached to or integral with the outer wall of the heavywalled tubing 27. The fins provide an extended heat transfer surface and are mounted along their outer top edges in a heavy-walled upper housing 49, throughout their central section in a thin-walled shroud 50 and along their lower outer edges in a lower housing 51. As will be seen from FIG. 3, the fins 48 positioned between the heavy-walled tubing 27 and the shrouds and housings define a plurality of fluid passages 54 through which a heat exchange fluid, e.g., ambient temperature air, is circulated. Circulation of ambient air in the embodiment illustrated in FIG. 1 is by means of a fan 60 having blades 61 mounted on a rotating member 62 which in turn is affixed to a pulley 63. The pulley is driven by a motor (not shown) through belt 64. The ambient air is passed at high velocity in contact with the tin surfaces after entering through a series of ports in upper housing 49, one of these ports being shown at numeral 65.

The lower bearing means 12 is constructed in accordance with well-known bearing design practice for sealed long-life grease lubrication and is held in place by retainer ring 73. In the apparatus of FIG. 1 key 76 is provided to effect the mechanical connection of the pulley 63 to the spindle. A pulley clamp washer 77 and nut 78 complete the assembly. The belt and pulley also, of course, drive the spindle as well as the fan.

in operation, a relatively low viscosity oil is introduced into chamber 26. With the rotation of spindle l and hence of skirt 23, the oil is pumped by centrifugal action through oil passages 22 in the rotor 21 to be hurled against the upper bearing means 11 and then to be drained by gravity along the stationary surface 34 of the pump wall. The heavy-walled tubing 27, as well as the fins 48, are formed of a metal having high heat conductivity at the temperature at which the bearing is to be maintained. Aluminum is the preferred material.

The heat which is transferred from the bearing components to the oil making contact with them is in turn transferred to the heavy-walled tubing and then to the fins which are cooled by the ambient air circulated through fluid passages 54. The spindle in an apparatus constructed in accordance with this invention experienced less than 3 F. rise above ambient temperature after reaching stable operating conditions. Human blood contained within a centrifuge mounted on the spindle suffered no damage due to heat or change in temperature.

It will be seen that a centrifuge constructed to have the spindle of this invention has marked advantages for use in processing blood in the manner previously described. The centrifuge may be operated in a temperature-controlled room while maintaining blood being centrifuged in it at the ambient temperature. ln most situations a battery of several such centrifuges would be operated in one room to provide the desired overall blood processing capacity; and all centrifuges and solutions would be operated at this room temperature.

Normally, the spindle will be operated at essentially room temperature, but it is of course within the scope of this invention to operate within any desired temperature range, the material for the tubing wall and fins, the bearing materials and oil, and the heat transfer fluid being all chosen to obtain the desired results at the predetermined temperature.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the constructions set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrated and not in a limiting sense.

I claim:

1. An apparatus adapted for rapid rotation at a constant,

predetermined temperature level, comprising in combination a. a rotatable spindle;

b. upper and lower bearing means adapted to maintain said spindle in alignment;

c. heavy-walled tubingmeans surrounding substantially the entire length of said spindle;

d. upper bearing cooling means comprising a pump adapted to circulate bearing oil in contact with said upper bearing means and then in contact with a portion of the inner wall of said tubing which defines an oil chamber around said Pu p;

e. extended heat transfer surface means in heat exchange relationship with said tubing; and

f. means for maintaining said heat transfer surface means at a predetermined essentially constant temperature,

whereby the heat flow path comprises said upper bearing means, said bearing oil, said heavy-walled tubing and said extended heat transfer surface means.

2. An apparatus in accordance with claim 1 including flexible mounting means associated with said upper bearing means.

3. An apparatus in accordance with claim 2 wherein said flexible mounting means comprises an annular elastomeric ring surrounding said upper bearing means.

4. An apparatus in accordance with claim 1 wherein said heavy-walled tubing is formed of aluminum.

5. An apparatus in accordance with claim 1 wherein said oil pump comprises:

1. a pump rotor having a plurality of oil passages adapted to conduct oil against said upper bearing means,

2. an oil-contacting surface defining the outer wall of said oil pump, and

3. oil dam means extending between said heavy-walled tubing means and said casing.

6. An apparatus in accordance with claim 1 wherein said extended heat transfer surface means are fins thermally bonded to the outer surface of said tubing and said means for maintaining said surface means at said temperature comprises means for circulating an essentially constant-temperature fluid in contact with said surfaces.

7. An apparatus in accordance with claim 6 wherein said fins are mounted within a cylindrical housing surrounding at least a portion of said spindle and said means for circulating said fluid comprises a fan adapted to circulate said fluid over said fins.

8. An apparatus in accordance with claim 7 wherein said cylindrical housing is in fluid communication with the ambient air surrounding said apparatus and said fluid is air whereby said apparatus, the liquid contained therein and all liquids passed therethrough are maintained at essentially ambient temperature throughout the processing of said liquid. 4

9. An apparatus in accordance with claim 1 including means for monitoring the oil level in said upper bearing cooling means. 

1. An apparatus adapted for rapid rotation at a constant, predetermined temperature level, comprising in combination a. a rotatable spindle; b. upper and lower bearing means adapted to maintain said spindle in alignment; c. heavy-walled tubing means surrounding substantially the entire length of said spindle; d. upper bearing cooling means comprising a pump adapted to circulate bearing oil in contact with said upper bearing means and then in contact with a portion of the inner wall of said tubing which defines an oil chamber around said pump; e. extended heat transfer surface means in heat exchange relationship with said tubing; and f. means for maintaining said heat transfer surface means at a predetermined essentially constant temperature, whereby the heat flow path comprises said upper bearing means, said bearing oil, said heavy-walled tubing and said extended heat transfer surface means.
 2. An apparatus in accordance with claim 1 including flexible mounting means associated with said upper bearing means.
 2. an oil-contacting surface defining the outer wall of said oil pump, and
 3. oil dam means extending between said heavy-walled tubing means and said casing.
 3. An apparatus in accordance with claim 2 wherein said flexible mounting means comprises an annular elastomeric ring surrounding said upper bearing means.
 4. An apparatus in accordance with claim 1 wherein said heavy-walled tubing is formed of aluminum.
 5. An apparatus in accordance with claim 1 wherein said oil pump comprises:
 6. An apparatus in accordance with claim 1 wherein said extended heat transfer surface means are fins thermally bonded to the outer surface of said tubing and said means for maintaining said surface means at said temperature comprises means for circulating an essentially constant-temperature fluid in contact with said surfaces.
 7. An apparatus in accordance with claim 6 wherein said fins are mounted within a cylindrical housing surrounding at least a portion of said spindle and said means for circulating said fluid comprises a fan adapted to circulate said fluid over said fins.
 8. An apparatus in accordance with claim 7 wherein said cylindrical housing is in fluid communication with the ambient air surrounding said apparatus and said fluid is air whereby said apparatus, the liquid contained therein and all liquids passed therethrough are maintained at essentially ambient temperature throughout the processing of said liquid.
 9. An apparatus in accordance with claim 1 including means for monitoring the oil level in said upper bearing cooling means. 